The present invention relates to a torque detector for use on a power transmission shaft, i.e. for use in power transmission from a drive shaft to a driven shaft of a machine such as an automobile.
The torque acting on such a transmission shaft changes as the load on the driven shaft fluctuates. Generally, it is possible to maintain the rotational speed of a machine at a selected value, or to obtain a desired speed, by changing the power output of the drive shaft in accordance with the fluctuating torque. A known torque detector determines the torque fluctuations by detecting speed changes of the machine, and adjusts the power output of the drive shaft in accordance with the detected change in torque.
Power transmission systems normally also include a gear reduction mechanism. Although the above known torque detector is effective when the reduction gear ratio is fixed, if the ratio is changeable, it is necessary to set a different reference speed for a desired torque every time the ratio is changed. Such a detector cannot function adequately in a machine having a stepless speed change gear mechanism, for example.
It is a general object of the present invention to provide a torque detector having a relatively simple construction, for detecting the torque acting on a power transmission shaft.